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CAPS Member Bios
Philip R. Christensen, Arizona State University (Co-Chair)
James Gregory Ferry, Pennsylvania State University (Co-Chair)
Sushil K. Atreya, University of Michigan
Amy C. Barr, Brown University
Richard P. Binzel, Massachusetts Institute of Technology
Ronald Breaker, Yale University
John Clarke, Boston University
Geoffery Collins, Wheaton College
Pascale Ehrenfreund, George Washington University
Linda T. Elkins-Tanton, Carnegie Institution for Science
James F. Kasting, Pennsylvania State University
Laurie A. Leshin, Rensselaer Polytechnic Institute
Stephen Mackwell, Lunar and Planetary Institute
Norman Pace, University of Colorado Boulder
Gary Ruvkun, NAS, IOM Harvard Medical School
Mark P. Saunders, Independent Consultant
Gerald Schubert, NAS University of California, Los Angeles
Norman H. Sleep, NAS Stanford University
Cristina Takacs-Vesbach University of Mexico
Roger V. Yelle, University of Arizona

PHILIP R. CHRISTENSEN is a Regents Professor and the Ed and Helen Korrick Professor in the School of Earth and Space Exploration at Arizona State University. His research interests focus on the composition, processes, and physical properties of Mars, Earth, and other planetary surfaces. Dr. Christensen uses spectroscopy, radiometry, field observations, and numerical modeling to study the geology and history of planets and moons. A major facet of his research is the design and development of spacecraft instruments, and he has built five science instruments that have flown on NASA’s Mars Observer, Mars Global Surveyor, Mars Odyssey, and the Mars Exploration Rover missions. Over the past decade he has studied urban environments and growth worldwide using satellite data and has developed an extensive K-12 education and outreach program to bring the excitement of science and exploration into the classroom. Dr. Christensen was awarded NASA’s Exceptional Scientific Achievement Medal in 2003, NASA’s Public Service Medal in 2005, and the G.K. Gilbert Award of the Geological Society of America in 2008. He is a fellow of the American Geophysical Union and the Geological Society of America. He received his Ph.D. in geophysics and space physics from the University of California, Los Angeles. Dr. Christensen has previously served as a member of the NRC Committee on Planetary and Lunar Exploration and as chair of the Planetary Science Decadal Survey’s Mars Panel.

JAMES GREGORY FERRY is the Stanley Person Professor of Biochemistry and Molecular Biology and director of the Center for Microbial Structural Biology at Pennsylvania State University. Dr. Ferry studies the enzymology and molecular genetics of anaerobic microbes from the  domain Archaeato learn about the mechanism and molecular evolution of enzymes and other fundamental cellular processes common to all three domains of life. His research has led to the discovery of several new enzymes with structures and reaction mechanisms novel to all of biology. Dr. Ferry’s research on ancient enzymes is contributing to an understanding of the origin and evolution of life and directly impacts the emerging field of astrobiology. Dr. Ferry has worked for numerous academic institutions before arriving at Pennsylvania State University, such as the University of Illinois, the University of Georgia, Virginia Polytechnic Institute and State University, and the Marine Biological Laboratory in Woods Hole, Massachusetts. He has served as co-chair of the NRC Committee on the Origins and Evolution of Life and as a member of the NRC’s NSF Graduate Panel on Biomedical Sciences.

SUSHIL K. ATREYA is professor of atmospheric and space science at the University of Michigan. His current research interests include composition, chemistry, structure, and the origin and evolution of planetary and satellite atmospheres, particularly the giant planets, Titan, Mars, and Venus, and the formation of solar systems. Dr. Atreya is at present a member of the science teams of Cassini-Huygens, Mars Science Laboratory, Juno-Jupiter Polar Orbiter, Venus Express, and the Mars Express missions. He has received the NASA Award for exceptional scientific contributions to the Voyager missions to the giant planets (1981), the NASA Group Achievement Award for outstanding scientific contributions with the Voyager Ultraviolet Spectrometer (1981, 1986, 1990), and NASA group achievement awards for outstanding scientific contributions with the Galileo Probe mass spectrometer and outstanding contributions to the Galileo Project at Jupiter (1996). He is a fellow of the American Association for the Advancement of Science, a member of the International Academy of Astronautics, and a Distinguished Visiting Scientist at the Jet Propulsion Laboratory. He is the author of Atmospheres and Ionospheres of the Outer Planets and Their Satellites and editor of Origin and Evolution of Planetary and Satellite Atmospheres and three other books. He has served as a co-chair of the Venus Exploration Analysis Group (VEXAG) and as a member of the Steering Committee of the Outer Planets Assessment Group (OPAG). Dr. Atreya has served three 1-year terms on the NRC’s Panel on Space Sciences of the Policy and Global Affairs Division’s Associateship Program and has also served on the Committee on the Assessment of Solar System Exploration.

AMY C. BARR is an assistant professor of geological sciences at Brown University. Previously, Dr. Barr spent 5 years as a research scientist at the Southwest Research Institute in Boulder, CO. After completing her Ph.D. at the University of Colorado, she held a post-doctoral position at Washington University, St. Louis. Her research interests focus on the formation and interior evolution of solid planets, with a special emphasis on planetary moons. She was a PI in the NASA Cassini data analysis program, outer planets research program, and planetary geology and geophysics program. Dr. Barr earned a B.S. in Planetary Science from the California Institute of Technology and a M.S. and Ph.D. from the University of Colorado, Boulder. She has previously served on the NRC’s Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System.

RICHARD P. BINZEL is a professor of planetary sciences, a Margaret MacVicar Faculty Fellow, and past chair of the Program in Planetary Science at the Massachusetts Institute of Technology. Dr. Binzel’s research interests include the collisional evolution of asteroids, planetary astronomy, and the physical parameters and surface features of the Pluto-Charon system. Dr. Binzel has conducted astronomical studies to investigate the compositional properties of asteroids passing near the Earth. He has also conducted intensive investigations of the distinct mineral absorption bands in the spectra of asteroids. He has earned a B.A. in physics at Macalester College and a M.A. and Ph.D. in Astronomy at the University of Texas, Austin. Dr. Binzel’s NRC service includes a term as a member of the Committee on Planetary and Lunar Exploration as well as chair of the Panel on Solar System Exploration for the Committee on Priorities for Space Science Enabled by Nuclear Power and Propulsion.

RONALD BREAKER (NAS) is the chair and Henry Ford II Professor of the Department of Molecular, Cellular and Developmental Biology at Yale University. He is jointly appointed as a professor in the Department of Molecular Biophysics and Biochemistry, and is an Investigator with the Howard Hughes Medical Institute. His graduate studies with Dr. Peter Gilham at Purdue University focused on the synthesis of RNA and the catalytic properties of nucleic acids. As a postdoctoral researcher with Dr. Gerald Joyce at The Scripps Research Institute, Dr. Breaker pioneered a variety of in vitro evolution strategies to isolate novel RNA enzymes and was the first to discover catalytic DNAs or “deoxyribozymes” using this technology. Since establishing his laboratory at Yale in 1995, Dr. Breaker has continued to conduct research on the advanced functions of nucleic acids, including ribozyme reaction mechanisms, molecular switch technology, next-generation biosensors, and catalytic DNA engineering. Most recently, his laboratory has established the first proofs that metabolites are directly bound by messenger RNA elements called riboswitches. Dr. Breaker’s research findings have been published in more than 100 scientific papers, book chapters, and patent applications, and his research has been funded by grants from the NIH, NSF, DARPA, the Hereditary Disease Foundation, and from several biotechnology and pharmaceutical companies. He is the recipient of fellowships from the Arnold and Mabel Beckman Foundation, the David and Lucile Packard Foundation, and the Hellman Family Trust. In recognition of his research accomplishments at Yale, Dr. Breaker received the Arthur Greer Memorial Prize (1997), the Eli Lilly Award in Microbiology (2005) and the Molecular Biology Award from the U.S. National Academy of Sciences (2006). Dr. Breaker has cofounded two biotechnology companies and is a scientific advisor for industry and for various government agencies. He serves on the editorial board for the scientific journals RNA Biology, RNA, Interdisciplinary Reviews: RNA, and Chemistry & Biology. He was elected to the NAS in 2013. He earned his Ph.D. in biochemistry from Purdue University. He has no prior NRC committee service.

JOHN CLARKE is a professor of astronomy at Boston University. His main research interests are in planetary atmospheres, their auroral and airglow emission, and ultraviolet space instrumentation. Prior to joining the faculty at Boston University, he worked at space science labs at the University of California at Berkeley, NASA’s Marshall and Goddard space flight centers, and the University of Michigan. Dr. Clarke served as the deputy project scientist for the HST project over 1984-1987, was a science team member on the Wide Field and Planetary Camera 2 project, and has participated in the flight of six sounding rocket experiments. He is presently PI for the Venus Spectral Rocket sounding rocket project, and a co-investigator on several space missions, including the Ultraviolet Imaging Spectograph Subsystem instrument on the Mars Atmosphere and Volative Evolution spacecraft, the PHEBUS experiment (Probing of Hermean Exosphere by Ultraviolet Spectroscopy) on the European Space Agency’s Bepi-Colombo mission to Mercury, and the ultraviolet imaging spectrograph instrument on NASA’s Juno Jupiter orbiter. Dr. Clarke received his Ph.D. from Johns Hopkins University. He was a member of the Giant Planets Panel of the NRC’s 2011 Planetary Science Decadal Survey.

GEOFFREY COLLINS is associate professor of geology in the Department of Physics and Astronomy at Wheaton College. In planetary science, his primary focus is on the geological features and geophysical processes of satellites in the outer solar system, including Ganymede and Europa at Jupiter and Enceladus, Dione, and Titan at Saturn. Beyond this focus, his research extends to geophysical phenomena on Venus, Triton, and Pluto. His contribution to the planetary science community includes membership on the science definition team for the Jupiter System Observer and NASA’s Outer Planet Assessment Group, as well as collaboration on the Galileo Image Team. Dr. Collins has served as principal or co-investigator for several research grants and has been awarded a Geophysical Research Letters Editor’s Citation for Excellence in Refereeing and the Brown Sigma Xi Research Prize. He received a B.A. from Carleton College and a Sc.M. and a Ph.D. from Brown University. He has previously served as vice chair of the NRC’s Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System.

PASCALE EHRENFREUND is research professor of Space Policy and International Affairs at the Space Policy Institute in Washington DC. During the last 15 years she has contributed as Principal Investigator, Co-Investigator and Teamleader to experiments in low Earth orbit, on the International Space Station as well as various ESA and NASA space missions, including astronomy and planetary missions. She is lead investigator of the NASA Astrobiology Institute (Node Wisconsin) and her research experience and interest range from biology to astrophysics. Dr. Ehrenfreund serves as the Project scientist of NASA’s O/OREOs satellite the first mission of the NASA Astrobiology Small Payload program currently in orbit. Dr. Ehrenfreund has served on several committees dealing with space strategy issues including the European Space Science Committee (ESSC), ESA’s Life and Physical Science Advisory Committee (LPSAC) and ESA’s Life Science Working Group (LSWG). Recently she served as European representative to the U.S. Space Studies Board Committee on the Origins and Evolution of Life and in the steering committee of the 2011 NRC Decadal survey on Planetary Science. Since 2010 she chairs the Panel on Exploration (PEX) of the Committee on Space Research (COSPAR) that supports space exploration activities, cooperative efforts and capacity building. She is the Vice President of the European Astrobiology Network Association EANA and a full member of the International Academy of Astronautics. Since 2011 she is member of the Space Advisory Group (SAG) of the European Commission. Dr. Ehrenfreund authored and co-authored more than 270 publications and edited 12 books. In Space Policy her interest is dedicated to international space cooperation. Dr. Ehrenfreund holds a Master in Molecular Biology from the University of Vienna (Austria), a PhD in Astrophysics from the University Paris VII/University Vienna (Austria), a Habilitation in Astrochemistry from the University of Vienna and a Master in Management & Leadership from Webster University (Netherlands). Asteroid 9826 Ehrenfreund 2114 T-3 orbits at 2.9 AU from the Sun.Dr. Ehrenfreund was a member of the Steering Group of the NRC’s 2011 Planetary Science Decadal Survey.

LINDA T. ELKINS-TANTON is the director of the Department of Terrestrial Magnetism of the Carnegie Institution for Science. Prior to her appointment as director in 2011 she was the Mitsui Career-Development Chair and assistant professor of geology at the Massachusetts Institute of Technology. Her research focuses on early differentiation of the terrestrial planets with implications for the formation of mantle reservoirs and the enhancement or suppression of convection, and large-scale dynamic processes in the upper mantle and lithosphere that lead to magmatism. Dr. Elkins-Tanton was awarded the National Science Foundation (NSF) Career Award in 2008, and was an NSF Kavli fellow. She has published dozens of papers as well as a six-book reference series called The Solar System. She is a member of the American Geophysical Union, the American Astronomical Society, Sigma Xi, and the Geological Society of America. She received her Ph.D. in geology and geophysics from the Massachusetts Institute of Technology. Dr. Elkins-Tanton has previously served on the Mars Panel of the NRC’s 2011 Planetary Science Decadal Survey.

JAMES F. KASTING is Evan Pugh Professor at Pennsylvania State University. He research interests include atmospheric evolution, planetary atmospheres and paleoclimates. Before coming to Penn State University in 1988, he spent two years at the National Center for Atmospheric Research in Boulder, Colorado and seven years in the Space Science Division at NASA-Ames Research Center. He is a Fellow of the American Association for the Advancement of Science, the International Society for the Study of the Origin of Life and the American Geophysical Union. He has published dozens of papers and two books, The Earth System (Prentice Hall 2009) and How to Find a Habitable Planet (Princeton University Press 2010) He earned his A.B. in chemistry and physics from Harvard University, and his M.S. in physics and atmospheric science from Michigan University where he also earned his Ph.D. in atmospheric science. He has served on the NRC’s Committee for US-USSR Workshop on Planetary Sciences (1988-1989) and the Panel to Review Terrestrial Planet Finder Science Goals (2004).

LAURIE A. LESHIN is the dean for the School of Science at Rensselaer Polytechnic Institute. She has previously worked as the deputy associate administrator of the Exploration Systems Mission Directorate at NASA Headquarters and, prior to that, as director of the Sciences and Exploration Division at NASA Goddard Space Flight Center. Her scientific interests include the volatile inventories and geochemical evolution of Mars and Earth; early solar system processes as recorded by primitive meteorites; prebiotic chemistry and water-rock interaction on asteroids; light element isotopic analysis using the ion microprobe; robotic and human exploration of the Moon, Mars, and beyond. She has extensive service on a number of committees including the President’s Commission on Implementation of U.S. Space Exploration Policy, the Solar System Exploration Subcommittee, the Jet Propulsion Laboratory Director’s Council, and the Curation and Analysis Planning Team for Extraterrestrial Materials. She has received the NASA Distinguished Public Service Medal, the Meteoritical Society’s Nier Prize, and the asteroid “4922 Leshin” was named in her honor. She earned a B.S. at Arizona State University and a M.S. and Ph.D. from the California Institute of Technology. Dr. Leshin has previously served on the NRC Committee on the Scientific Context for Space Exploration.

STEPHEN MACKWELL is the director of the Lunar and Planetary Institute in Houston, Texas. He is adjunct professor of Earth Science at Rice University. Prior to his current appointment, Dr. Mackwell served as the director of the Bayerisches Geoinstitut at the University of Bayreuth, Germany. Dr. Mackwell has served as program director for geophysics, Division of Earth Sciences, National Science Foundation (NSF; 1993-1994); as member, group chief, and panel chair of the review panel for NASA’s Planetary Geology and Geophysics Program; as expert reviewer for the Department of Energy’s Geosciences Research Program (1993); and as expert consultant for the Division of Earth Sciences, National Science Foundation (1995). Dr. Mackwell conducts laboratory-based research into the physical, chemical, and mechanical properties of geological materials under conditions relevant to the mantle and crust of Earth and other terrestrial planets. He served on the NRC Committee on New Opportunities in Solar System Exploration, the NRC Committee to Review Near-Earth-Object Surveys and Hazard Mitigation Strategies, the NRC Committee on the Planetary Science Decadal Survey, the NRC Planning Committee on Lessons Learned in Decadal Planning in Space: A Workshop, and the NRC Committee on Review of the Draft 2014 Science Mission Directorate Science Plan. He currently serves on the NRC Committee on Astrobiology and Planetary Science.

NORMAN PACE (NAS) is a professor at the University of Colorado in the Department of Molecular, Cellular, and Developmental Biology. Dr. Pace is an internationally recognized expert in nucleic acids and associated enzymes. His studies of ribosomal RNA structures have set new standards for the definition of phylogenetic relationships among organisms. His research interests include RNA enzymes, RNA processing, macromolecular structure, molecular evolution, and microbial ecology. Dr. Pace formerly served as a member of the Board on Scientific Counselors for the National Center for Biotechnology Information, National Library of Medicine. He is a Fellow of the American Association for the Advancement of Science and the American Academy of Microbiology. He earned his Ph.D. in microbiology from the University of Illinois at Urbana Champaign. In addition, he has served on NRC committees including the Committee on the Origins and Evolution of Life in the Universe, the Committee for a Review of Programs to Determine the Extent of Life in the Universe, and the Steering Group for the Workshop on Size Limits of Very Small Microorganisms.


GARY RUVKUN (NAS, IOM) is professor of genetics at Harvard Medical School. His lab investigates neuroendocrine control of C. elegans development, metabolism and longevity, as well as control of temporal pattern formation by heterochronic genes. He also has begun new studies on the genetic control of molting and neurotransmitter tranport. His lab has also started work with the Church laboratory and engineers at MJ Research and the MIT Center for Space Research to develop a miniature thermal cycler and protocols to send to Mars in search of microbial life. As a postdoc he worked with Bob Horvitz at MIT and Walter Gilbert at Harvard, where he explored the heterochronic genes that control the temporal dimension of development. This work led to the discovery of the first microRNA genes and their mRNA targets by the Ambros and Ruvkun laboratories, the discoveries by the Ruvkun laboratory that the mechanism of microRNA regulation of target mRNAs is post-transcriptional and that some microRNA genes are conserved across animal phylogeny. Dr. Ruvkun is a graduate of UC Berkeley (A.B. Biophysics) and Harvard University (Ph.D. Biophysics). He is a member of the NAS and the IOM. He has served on the NRC’s KFoS Five-Year Review Committee, the Organizing Committee for the Eleventh Annual Symposium on Frontiers of Science, and the Committee on the Origins and Evolution of LifeCRISTINA TAKACS-VESBACH is an associate professor in the Department of Biology at the University of New Mexico. Dr. Takacs-Vesbach conducted her graduate work in microbial ecology and performed research on the factors affecting bacterioplankton distribution and productivity in the Dry Valley Lakes of Antarctica. Her post-doctoral work focused on the microbial phylogenetic and physiological diversity of hydrothermal springs. Dr. Takacs-Vesbach is the recipient of the outstanding doctoral student award of the Montana State University Foundation, the John Wright Award for Limnology, and the Gary Lynch Award from the MSU Department of Biology. Her current research focuses on molecular microbial ecology—especially microbial diversity and productivity in extreme environments. Her NRC experience includes service on Committee on Preventing the Forward Contamination of Mars, the Planning Committee for the International Polar Year, and the Committee on the Origins and Evolution of Life.

MARK P. SAUNDERS is an independent consultant. Since retiring from NASA in December 2008, he has been consulting to various NASA offices providing program/project management and systems engineering expertise. This has included support to the Office of Chief Engineer, the Office of Independent Program and Cost Evaluation, the Mars Program and the Science Office for Mission Assessments (at Langley Research Center). He has participated in the rewriting of NASA,s policy on program/project Management; advised and supported the Agency’s independent program/project review process; and has supported the review of various programs and projects. At NASA Headquarters he served as director of the independent program assessment office, where he was responsible for enabling the independent review of the Agency’s programs and projects at life cycle milestones to ensure the highest probability of mission success. At NASA’s Langley Research Center he was initially the deputy director and then the director, Space Access and Exploration Program Office (SAEPO) and had the responsibility for planning, directing and coordinating the center's research, technology, and flight programs for advanced aerospace transportation and human/robotic exploration systems. Prior to this he was the Manager of Exploration programs and led all LaRC space exploration research and development activities supporting the agency’s Aerospace Technology (AST), Human Exploration and Development of Space (HEDS) and Space Science Enterprises (SSE). At the office of space science he served as program manager for the Discovery Program, and at the space station freedom program operations he served as special assistant to the deputy director. He received the Presidential Meritorious Rank Award in 2008, Outstanding Performance awards: 1982, 1994- 2008 and the NASA Outstanding Leadership Medals in 1998, 2004, 2006. He earned his B.A. at the Georgia Institute of Technology in industrial engineering. He has no prior NRC committee service experience.

GERALD SCHUBERT (NAS) is a professor in the Department of Earth and Space Sciences and in the Institute of Geophysics and Planetary Physics at the University of California, Los Angeles. Dr. Schubert’s research interests center on theoretical studies of the internal structures of the giant planets and their major satellites. He has been associated with many spacecraft missions, including serving as an interdisciplinary scientist and co-investigator for the Atmospheric Structure Experiment on Galileo; member of the Magellan Radar Investigation Group; interdisciplinary scientist for Pioneer Venus; co-investigator for Apollo 16’s Lunar Surface Magnetometer; and co-investigator for Apollo 15 and 16’s subsatellite magnetometers. Dr. Schubert has served as a member of the NASA Planetary Geology and Geophysics Management Operations Working Group; the Lunar and Planetary Geoscience Review Panel and Geophysics Group Chief; and the Planetary Atmospheres Review Panel and Dynamics Group Chief (1995). He received his B.E.P and M.A.E. in engineering physics and aeronautical engineering from Cornell University and his Ph.D. in engineering and aeronautical sciences from the University of California, Berkeley. He previously served on the NRC Committee on Planetary and Lunar Exploration, the 2002 planetary science decadal survey committee, the Committee on New Opportunities in Solar System Exploration, the Satellites Panel of the 2011 Planetary Science Decadal Survey, and the Steering Group of the Committee on NASA Technology Roadmap.

NORMAN H. SLEEP (NAS) is a professor of geophysics at Stanford University. Dr. Sleep’s research interests include studying convection at the base of the lithosphere and the interaction of the lithosphere with mantle plume material. He is also currently investigating the microphysics of friction and applying the results to nonlinear attenuation and ground damage by strong seismic waves. Dr. Sleep is a fellow of the American Association for the Advancement of Sciences, the Geological Society of America, and the American Geophysical Union. He has received a number of awards for his work including the James B. Macelwane award, the George P. Woollard Award from the Geological Society of America, and the 2008 Wollaston Medal from the Geological Society of London. Dr. Sleep earned a B.S. in mathematics from Michigan State University and a M.S. and Ph.D. in geophysics from the Massachusetts Institute of Technology. He has previously served on the NRC Committee on Earth Resources, the Committee on Planetary Biology and Chemical Evolution, and has served a NAS Section liaison.

ROGER YELLE is a professor of planetary science at the University of Arizona. Dr. Yelle’s research studies the atmospheres in the solar system and in extrasolar planetary systems. He analyzes telescopic and spacecraft data and constructs theories and models to determine the composition and structure of atmospheres and their interaction with surfaces and interplanetary space. Some of his current projects include the study of chemical, thermal and dynamical processes in Titan’s upper atmosphere using primarily data from the Cassini mission to the Saturn system. He is also investigating escape processes on Titan and extra-solar planets. Dr. Yelle is also a member of the Cassini Ion Neutral Mass Spectrometer Team and chairperson on the Cassini Titan Atmosphere Model Working Group (TAMWG). He is a member of the American Geophysical Union, American Astronomical Society, and European Geophysical Society and has been awarded the Harold C. Urey prize from the Division for Planetary Science of the American Astronomical Society as well as a number of Group Achievement Awards from NASA. Dr. Yelle earned a B.S. in physics from the Worcester Polytechnic Institute and a M.S. and Ph.D. from the University of Wisconsin-Madison in physics. He has previously served as a member of the NRC Task Group on the Availability and Usefulness of Space Mission Data and the Committee on Planetary and Lunar Exploration.